The testes must be kept cool for the proper production of sperm. One way the human body achieves this is to house them outside the body. Another is to have a network of veins surrounding the artery pumping blood into the testis: the veins take the heat away in a “counter-current” heat exchange similar to a radiator. (The human body is an amazing piece of engineering.)

Arteries don’t need to worry about moving blood; there’s a huge amount of pressure coming from the heart to help with that. But once the blood goes through the capillaries and into the veins, getting back to the heart isn’t easy. Veins have little valves to help hold the blood while it pulses its way back. If those little valves start to separate, the vein expands, causing the condition known as a “varicose vein.” Varicose veins can happen in many places in the body, often visibly in the skin of the legs, but, believe it or not, also in the scrotum. And if varicose veins develop in the scrotum, they can disturb the counter-current heat exchange. The testes then get hot, posing a problem for developing sperm cells.

Varicose veins in the scrotum are called a “varicocele,” and there are three kinds. A grade I varicocele can’t be felt or seen without equipment like ultrasound. Almost all experts now consider grade I varicoceles to be unimportant. Varicoceles that can be felt (grade II) or visible by the naked eye (grade III) are the ones that may cause problems with sperm production. Some men have such high sperm production that their varicoceles don’t significantly alter their chance of making women pregnant. But many men’s testes are affected by grade II or III varicoceles.

Inside of a man, the left vein draining the testis back towards the heart is longer than the right. As a result, varicoceles are most often found in the left scrotum. Sometimes, they’re on both sides, and infrequently, they’re on the right side alone. A right sided varicocele that suddenly appears in adult life is worrisome, as it may be a sign of kidney cancer.

What can be done about a varicocele that may be throwing a wrench into the sperm factory? A urologist can tie or clip the veins in a procedure called “varicocelectomy,” or an interventional radiologist can inject material into the veins to block the flow of blood.

A man straining his abdomen as during heavy lifting can cause the varicose veins to fill and perhaps enlarge, but it is unlikely to have caused the varicose veins in the first place. If the veins become very large, they can become painful, but that is rare. Usually they’re painless.

I have bad varicose veins in my right testicle and it feels like I am developing a ball of veins underneath my right testicle. My left testy is fine . Just two days ago it became rather sensitive and a little achy. I went to cross my right leg over my left and it hurt really bad. I am 24 yrs. old. Should I be worried?

I’m sorry, Jesse, but I can’t answer personal questions about your own health. Please read the FAQ. There you’ll find that I always recommend a man see his doctor. I also urge people to read through the comments. You’ll see that I’ve answered personal questions similarly above.

Is there a correlation with riding bicycles and increased risk of contracting varicocele? Just curious if the heat and pressure from bicycle seat has any causal effect on this condition.
Also, what would a man look and feel for in a self exam that would trigger a concern to schedule a doctor visit? Can you recommend a link with pictures of grade 3 varicocele?
Thanks for the info!

Hi Mr. G, there aren’t good studies associating bicycling and varicocele, and the connection doesn’t make biological sense. For the second question, any guy concerned about whether or not he has a varicocele should see a doctor. Good luck!

This is a pretty old post, but I leave the comments section open. If someone has a question, I’ll do my best to answer it. Kinds of questions that I can and can’t answer are in the FAQ. I’ve received so many questions about a man’s personal health that unfortunately I can’t answer, and those I’ve stopped answering as I’m sorry, but please read the FAQ…

Hi Jeff, nothing is ever 100% in medicine. For the first question, as I wrote, “Some men have such high sperm production that their varicoceles don’t significantly alter their chance of making women pregnant.” For the second question, nothing is certain in medicine, and nothing is automatic

Hi doctor. When a varicocele forms on both the left and right, does it happen at relatively the same time? Is it possible for a varicocele to form on the right years after one has already formed on the left? Thanks in advance!

Great advice. But say if a varicocele appears on the left at age 14, during puberty. Is there a chance of it developing on the right as well, somewhere down the road, say age 16…or will a varicocele form on both sides at relatively the same age, at the same time, IF the person has bilateral varicocele?

Basically, can a new varicocele form on the right years after one has already been on the left?

Typically, I don’t answer the same question twice But this one is really, really important. If a man has a new varicocele, he needs to see his doctor, because it can mean possibly deadly kidney disease. Any new varicocele or any sort is really concerning.